"Orval Fairbairn" wrote in message
news
In article ,
"Eric Miller" wrote:

"RobertR237" wrote in message
...
PS: This is a simple answer to your question but many factors are
involved.
The effort to increase a 200 hp engine to 260 hp may or may not be
worth
the
effort and the 30% increase in hp wil not produce an equilivent
increase
in
thrust or speed. I don't remember the formula for calculating the
increase but
it is far less than anticipated.

Speed increases at about the cube root of the HP increase, so:

(260 / 200) ^ (1 / 3) = 1.091 or about 9% faster with 30% more HP

But other factors to consider are the increased weight of a larger
engine,
the increased fuel burn, and the weight of that fuel.

Eric



Extra horsepower converts directly into rate of climb, assuming the same
weight and airspeed. Fuel consumption rises approximately in proportion
to horsepower; stability decreases.

Other factors in boosting phenomenal horsepower out of small packages:

Increased thermal load
Increased stress on all parts of the engine
Some high RPM ranges may not yield usable thrust because the prop tips
are in the transonic range, where prop efficiency decreases greatly.

And in the case of a rotary, you WILL be spinning the engine around 6000 or
so RPM. This means you must also use a PSRU to drop the RPM down to
something usable for the prop. The nice thing is, 6000 shaft RPM is only
2000 rotor RPM. The 13b can handle 6-8 grand with no problems.

Phillip